I. Background

Access to graphic materials in libraries and archival collections frequently has
been limited to retrieval by subject content and names of creators. Although
catalog records often include information on genre and physical
characteristics, researchers have not always had ready access to it. A
student of lithography, for example, may be compelled to consult reference
books for names of printmakers likely to have produced lithographs, then to
search a library's catalog of prints for artists' names, and, finally, examine
each catalog record to find those for lithographs. A scholar investigating the
cultural impact of photographically illustrated books may be forced to rely on
a few published bibliographies, in-house example files, staff memory, and
chance discoveries to locate examples of such works. As graphic collections
grow and catalog records accumulate, it is clear that additional access points
greatly facilitate research related to functional categories, production contexts,
and artifactual aspects of graphic materials.[1]

A single list of standard terms from which catalogers and researchers can
choose indexing and retrieval vocabulary was needed, along with widely
accepted provisions for applying the terms as access points. The first edition
of Descriptive Terms for Graphic Materials: Genre and Physical
Characteristic Headings (GMGPC) appeared in 1986. Before
then, the lack of such a list and cataloging guidelines was a problem because
of the great variety of media and pictorial types and because of the broad
range of users of graphic materials, whose knowledge and experience vary.
While an extensive and often informal vocabulary is employed in the descriptive portion of the catalog record, indexing terms should be controlled.
Reconciling variant terms by designating a preferred indexing term not only
simplifies the cataloger's task but also makes retrieval more efficient. For
example, the standard term "dry plate negatives" collocates "silver gelatin
glass negatives," "glass plates," and "dry plates." Furthermore, the terms for
indexing graphic materials can be used most effectively when presented within
the structure of a thesaurus designed to establish relationships and guide
users.

While TGM II can be used in a variety of cataloging systems, it
was created primarily in response to the needs of institutions using the
communications format called MAchine-Readable Cataloging (MARC) for their automated catalog records. In 1979, the Independent Research Libraries
Association (IRLA) recommended in "Proposals for Establishing Standards for
the Cataloguing of Rare Books and Specialized Research Materials in
Machine-Readable Form" the addition of two new fields to the MARC format for
terms indicating genre and publishing/physical aspects. In 1980, the field 655
was authorized for genre headings and in 1984 field 755 was authorized for
physical characteristic headings. In 1995, the need and practicability for keeping these two fields of data separate was determined to be insufficient, and the 755 field was made obsolete.[2] The 655 "Form-Genre" field is now defined for all types of material in the USMARC Format for Bibliographic Data.[3]

IRLA asked the Standards Committee of the Rare Books and Manuscripts Section
of the Association of College and Research Libraries to develop thesauri appropriate
for rare books and special collections. The lack of vocabulary to index book
illustrations led the Committee to encourage staff of the Library of Congress
Prints and Photographs Division to expand and integrate several of their genre
and physical description lists into a thesaurus constructed according to guidelines
set out by the American National Standards Institute.[4] The result was Descriptive
Terms for Graphic Materials: Genre and Physical Characteristic Headings
with 513 authorized terms and 290 cross references. When the second edition,
TGM II, closed for publication in June 1994, it had 600 authorized
terms and 448 cross references, a 15% increase in postable terms. In July 2004,
there are 660 main terms.

The Library of Congress MARC Standards Office prepared Discussion Paper
no. 82 (December 1994) for American Library Association (ALA) Machine-Readable
Bibliographic Information Committee (MARBI), weighing the need for the 755
field. The discussion paper was sponsored by the Bibliographic Standards Committee
of the Rare Books and Manuscripts Section (RBMS) of the Association of College
and Research Libraries Division (ACRL) of ALA and the Subject Analysis Committee
(SAC) of the Cataloging and Classification Section of the Association for
Library Collections and Technical Services (ALCTS). As a result of the discussion
field 755 was made obsolete in 1995. Go Back

USMARC Format
for Bibliographic Data, prepared by Network Development and MARC
Standards Office (Washington, D.C., Library of Congress, 1994). Includes guidelines
for content designation. New and replacement pages are issued periodically.
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